The invention relates to the general field of dyeing of hair. For dyeing of hair, the so-called oxidative dyes are of preferred interest because of their intense color and very good fastness properties and are obtained by oxidative coupling of a developer component with a coupler component.
Numerous particular demands are put forward with respect to the oxidative dyes used for dyeing human hair. They must be unobjectionable toxicologically and dermatologically and permit one to obtain colorings to the desired intensity. Furthermore, it is necessary to provide a wide range of various coloring shades through the combination of suitable developer components and coupler components. Moreover, the obtainable hair colorings must meet a good fastness to light, permanent waving, acid and rubbing. In any case, these hair colorings must remain stable without the influence of light, chemical agents and rubbing for a period of at least 4-6 weeks. As developer substances, usually 4-aminophenol, 1,4-diaminobenzene as well as its derivatives, 2,5-diaminotoluene and 2,5-diaminoanisole are used. A certain relevance is also attributed to 1,4-diaminobenzene derivatives, 2,5-diaminobenzyl alcohol and 1,4-diamino-2-(.beta.-hydroxyethyl)-benzene.
The preferably used coupler substances are resorcin, 4-chlororesorcin, m-aminophenol, 5-amino-2-methylphenol, 1-naphthol, m-phenylenediamine and its derivatives as for example 2-amino-4-(.beta.-hydroxyethylamino)-anisole or 2,4-diaminophenoxyethanol. Moreover, also 4-hydroxy-1,2-methylenedioxybenzene and 4-(.beta.-hydroxyethylamino)-1,2-methylenedioxybenzene can be used as coupler substances.
The m-pheneylenediamine and its derivatives have gained some importance as so-called blue couplers because of their ability to produce blue tones upon the oxidative coupling with 1,4-diaminobenzene and 1,4-diaminobenzene derivatives. The color character, the stability and also the intensity of the so produced blue tones are determined by the chemical constitution of the used 1,4-diaminobenzene derivatives as well as by the chemical structure of the m-phenylenediamine derivatives. Although very intense blue tones can be produced during the use of known blue couplers like 2,4-diaminoanisole, 2,4-diaminophenetole and 2,4-diaminophenoxyethanol; however, these blue tones show a red fraction. This red fraction is especially undesired for producing mat black tones in combination with the developers 1,4-diaminobenzene or 2,5-diaminobenzene alcohol. It is true that these mat black tones can be produced with m-phenylenediamine, but it is to be noted that the obtained black tones are very unstable and change their color to rust brown after some weeks.